Method for quantification of oils and sebum levels on skin using the Sebumeter(®)

The Sebumeter(®) is widely used in both cosmetic and medical research, for measuring changes in sebum levels on skin. It is commonly reported that the units correlated to a mass of sebum on the skin in μg cm(-2) ; however, validation for this has not been published. Also, its use for assessing the presence of other oily materials which are widely utilized in topical skincare products on skin has not been widely discussed. Determining a calibration scale and whether the response of the device is linear with the level of oils present enables quantification of the output of the device, and would validate the device for claims substantiation.

Different doses of a variety of oily materials (paraffin oil, white soft paraffin, capric-caprylic triglyceride, 350cSt silicone fluid and synthetic sebum) were applied to skin, and the Sebumeter(®) used to collect and quantify them. The mass per square centimetre of the oily material delivered to the skin was then compared to the Sebumeter(®) output to develop calibration curves for the different materials. Measurements were carried out on a single volunteer as this work was to verify the concept of quantitative oil assessment using the device.

A linear correlation between the mass of the oily material and the Sebumeter(®) output was seen for all the materials tested. However, the absolute response of the device was different for each material, and the output values did not directly give the mass of material on the skin in μg cm(-2) . As part of the calibration, it was also demonstrated that to remove all the oily material from a given area of the skin required multiple 30-s applications of the Sebumeter(®) cartridge.

The Sebumeter(®) is a precise analytical instrument capable of quantitative measurement of deposition of oily materials onto skin from topical products (down to the μg cm(-2) level), as well as its traditional use of measuring sebum levels. However, the output values do not directly correlate with the mass of oil present, and generation of a calibration curve is necessary for any ingredient of interest to produce quantitative data for claim support and formulation development.